It's not the quietest fan out there, but depending on your motherboard, you can set the CPU temperature monitor interval to a longer period. I ended up having to do that for my 2700X (with the Asus motherboard in my signature) as the AMD's XFR and Precision Boost was causing my fan to spin up and down pretty much all the time. I think I set the temperature polling at 10 seconds, which took care of the problem. It's likely the constant RPM change with the fan is what you are noticing.
Additionally, you can set a custom fan profile in your BIOS, and that can help as well.